1. Field of the Invention
The present invention relates to a light emitting device for an electronic device, provided with a Digital Light Processing (DLP) projector and a display unit, in which the light generated by the operation of the DLP projector is re-used as a backlight light of the display unit, as a Liquid Crystal Display (LCD).
2. Description of the Related Art
Electronic devices have been recently miniaturized and manufactured as multi-functional devices according to consumers' requirements. Also, due to the digitalization of data, multi-functions, including voice communication, radio-listening, downloading Motion Picture experts' group audio layer-3 (MP3) music via internet connection, acquiring information (e.g., various data and images), etc., can be easily achieved via electronic devices, such as a portable communication device, a Personal Digital Assistant (PDA), a computer, a notebook computer, etc.
Moreover, as a data output device for an electronic device, a display unit such as a Liquid Crystal Display (LCD) is generally used. In general, a keypad used for data input includes the arrangement of multiple keys. A portable communication device from among such electronic devices is divided into various types of terminals according to the appearance of the device: a bar-type terminal, in which a communication device, and input/output devices are provided in one housing; a flip-type terminal including a bar-type terminal with a rotatably provided flip cover; a folder-type terminal with a pair of housings, the housings being rotatably provided in a direction toward and away from each other; and a sliding-type terminal in which a pair of housings are adapted to slide while facing each other.
Meanwhile, mobile communication services were limited to voice calling and transmission of short messages in early stages, but has shown a tendency to spread into various service areas, including customized videos, music videos, reproduction of movie/music files, television, games, and mobile banking, with the continuing development of mobile communication technologies.
In order to enjoy multimedia services, such as customized videos, music videos, reproduction of movie/music files, TV watching, it is necessary to view a screen displayed through a display unit.
However, since the display unit of the portable communication device has a limited screen size, a projector capable of displaying a large screen can be used by mounting the projector in the portable communication device.
As mentioned above, as the projector mounted in the portable communication device, a DLP (Digital Light Processing) projector is mainly used for miniaturization.
The DLP projector uses a DMD (Digital Micromirror Device) chip, and the DMD chip refers to a semiconductor optical switch having microscopic mirrors arranged on its surface. A DLP-type projector blocks or transmits the light reflecting from the surface of a DMD chip via a circuit board, and displays an image by adjusting the reflective angle based on such a signal.
In the DMD chip, a microscopic aluminum-alloy mirror is provided above one cell of an SRAM (Static Random Access Memory), and the microscopic mirror operates by the electrostatic operation of the underlying memory.
The DLP-type projector employing the DMD chip is divided into a single panel type projector, and a three panel type projector separately using red (R), green (G), and blue (B). Both the single and three panel type projectors are effective digital type projectors and have very high color reproducibility, compared to a conventional method.
The DLP-type projector is advantageous in that the DLP-type projector has a long lifetime, a high sharpness, and can directly reproduce an input digital image signal with an original image quality without additional correction.
As shown in FIG. 1, a DLP projector 1 uses a lamp as an external light source. The DLP projector 1 schematically includes a light emitting diode (LED) 2 emitting red (R), green (G), and blue (B) lights, an optical engine unit (a DMD chip) 3 which converts a light A1 incoming from the LED 2 into an appropriate image signal based on an external input image signal, a projection lens 5 for projecting the light A1 of the image signal converted by the optical engine unit 3 on a screen 4, an optical engine supporter 6 for supporting the LED 2, the optical engine unit 3, and the projection lens 5.
However, as shown in FIGS. 2 and 3, a microscopic mirror 3a of the optical engine unit 3 in the DLP projector is continuously driven in left/right directions with an angle of +/−θ to express an image signal, and is repeatedly placed in a reset state D1 as an intermediate operation state. As shown in FIGS. 2 and 3, the microscopic mirror 3a may be composed of a plurality of independently moving mirrors.
Herein, when the microscopic mirror 3a is placed in the reset state D1, the light A1 of the LED 2 leaks out and is wasted.
In other words, in operation of an electronic device provided with the conventional DLP projector and the display unit as described above, since the display unit (LCD) and the projector must be operated at the same time, the power consumption of the product is increased, thereby reducing a battery usage time of the electronic device.
Accordingly, there exists a need for a light emitting device that converges, for example, the LED 2's light A1 wasted by the reset state D1 of the microscopic mirror in the use of the conventional DLP projector, and re-uses the light A1 as a backlight light of the display unit, which may be an LCD in an electronic device.